1. Field of the Invention
This invention relates to the successful controlling of the stereochemistry of 1-O-acylation of appropriately protected D-glucose to synthesize anomerically pure 1-.alpha.- and 1-.beta.-esters of 2,3,4,6-tetra-O-benzyl-D-glucopyranose and anomerically pure 1-.alpha.- and 1-.beta.-D-glucose esters.
2. Description of the Prior Art
The prior art does not provide any easy procedures for the preparation of glucosyl esters, especially the .alpha.-D-anomers. In fact, the only known examples are the gallate and the mesitoate which were made by indirect routes in low yields. The gallate was prepared in 5% yield by the procedure of Schmidt (Justus Liebigs Ann. Chem., 587, 63, 1954), and the mesitoate in 17% yield by the procedure of Fletcher (J. Am. Chem. Soc., 82, 3215, 1960). Such procedures for the preparation of 1-.alpha.-glucosyl esters were chosen because the hindered ester functions are less likely to rearrange, that is, migrate from position 1 to position 2, under the nonneutral deblocking conditions utilized. Furthermore, Fletcher could not extend either procedure to less hindered systems because of the lack of stereospecificity in the acylation procedure employed and loss of desired product through rapid migration of the unhindered ester function from C-1 to C-2 under the non-neutral deblocking conditions (J. Am Chem. Soc., 78, 2849, 1956).